Method of producing artificial thread



Oct. 18, 1938. PARKER 2,133,715

METHOD OF PRODUCING ARTIFICIAL THREAD Original Filed Aug. 25, I933 'LLITo bwc/fet ATTORNEY Patented Oct. 18, 1938 UNITED STATES PATENT orncs2.133.115 rmrnon or raonncmo ARTIFICIAL 'rrmnsn poration of DelawareApplication August '23, 1933, Serial No. csasss Renewed March 16, 1938 6Claims. (01. 18-54) This invention relates to the manufacture of hightenacity yarn, thread, filaments, straw, ribtion or the like.

Recently, there has been proposed a method of producing a new type ofregenerated cellulose threads possessing a very high dry tenacity, i. e.in excess of 2 grams per denier, by spinning viscose into a bathcontaining more than 50% sulphuric acid. According to this procedure,tension is applied to the freshly formed thread by passing it between aseries of glass rods so placed that the thread must bend therearound inits travel. Owing-to the great strain imposed upon the weak and tenderstructure of the plasticized 15 thread by the frictional effect of theglass rods, the speed of spinning is relatively low and many of thefilaments become damaged and broken, so that the ultimate product isseldom, if ever, free from undue broken filaments and is not only poorin quality but greatlyreduced in strength. For thisreason'alone, such aprocess is of doubtful commercial value. Furthermora'when tension isapplied by means of sliding friction, it is necessary to spin at verylow speeds, which is also a serious drawback to commercial success.Also, the yarn produced by such a procedure possesses undesirablenon-uniformity of physical and chemical properties which are present'inall yarns subjected in spinning to an irregular stretch, be-

30 cause the spinning tension must necessarily vary due to theimpossibility of keeping the spinning conditions exactly the same at alltimes.

I have found that I can overcome the abovementioned disadvantages byspinning a thread in 35 a spinning bath containing a plasticizingingredient, such as a bath containing from at least 45%-85% or moresulphuric acid, and applying a substantially uniform tension, preferablyin stages, to the coagulated and partially regener- 40 at'ed threadwithout subjecting said thread to severe sliding friction, such as thatdeveloped when a thread is dragged under tension around a rod or otherguide, and produce a strong thread of higher quality than that which hasbeen here- 45 tofore produced as well as spin at a much higher speedthan has been considered possible up to the present time.

' It is, therefore, an object of this invention to provide a method ofspinning a thread in a plas- 50 ticizing bath and applying asubstantially uniform tension, preferably in stages, to the threadwithout subjecting said thread to severe sliding friction, such as thatdeveloped when a thread is dragged under tension around a rod or other55 guide, thereby producing a uniform thread of improved strength andelongation which will dye more uniformly and which is substantially freefrom broken filaments.

Another object of my invention is to provide a method for orderly andcommercially spimiing at high speeds high tenacity threads. ofregenerated cellulose in a plasticizing bath.

A still further object of my invention is to produce a high qualitythread of good strength,

elasticity and endurance which is especially 10 suited for such uses asthe manufacture of cords or fabrics for use in vehicle tires, steamhose, of reinforcing fabrics, brake linings, etc. 1

Other objects will become apparent from the following description,appended claims and accompanying drawing in which:

Figure l is a plan view of an illustrative diagrammatic set-up forcarrying out one embodiment of the instant invention; and

Figure 2 is a front elevation of an illustrative go diagrammatic-set-upfor carrying out another embodiment of the instant invention.

In accordance with the principles of this invention, I spin a viscosesolution into a plasticizing bath, such as one containing 45%-85% ofsulphuric' acid, and impose on the thread, at one or more points in itspath of travel from the spinneret to the draw-off device, atension'which is substantial,.uniform, constant and substantially freefrom any undue or substantial sliding frlction, such as that developedwhen a thread is dragged under tension under a rod or other guide. Afterpassage through the acid bath, further action of the acid is checked,such as by passing the thread through a water bath.

As illustrative means for imposing the substantial, uniform and constanttension, I use rotatably mounted rollers which are rotated solely bythread passing therearound and provided with means for developing aresistance to rotation in 40 the bath, such as those described inBritish Patent No. 318,258 and in United States PatentNo. 1,878,455. Inthe preferred form of the invention, I utilize aplurality of the guidesarranged in series and with or without other types of guides, such asthose of the friction type. For example, two or three floating guiderollers, such as are shown and described in United States Patent No.1,878,455, may be used alone and/or in combination with one or morerotating guides, 5 such as is described in the British patent supra.

The rotating guides above mentioned are so devised and constructed as tocompensate, as explained in application Serial No. 655,738, for thevarying differences in a viscose concentration of bath, temperature,etc., that always exist in the commercial manufacture of regeneratedcellulose threads by speeding up or slowing down,-in accordance with theease or difliculty of tensioning the freshly formed thread.

In the preferred form of this invention, I employ a viscose solution ofthe type specifically described in my copending application Serial No.676,463. This viscose solution may be prepared by using such-materials,apparatus and procedures as 'will not cause the resulting viscose to becontaminated with the undesirable im urities. According to oneprocedure, the viscose, after ripening, is conducted to the extrusiondevice through equipment made of a material which will not be corrodedby the viscose, will not contaminate the viscose and will not promotethe gelation of the viscose. The viscose which is preferred in theinstant invention may also be of the ordinary type which, afterconsiderable filtration such as through a nickel filter press, isdelivered to the extrusion device without change in quality, such as bybeing conducted, after leaving the nickel filter press, throughequipment made of any material such as will not be corroded by theviscose, will not contaminate the viscose and will not promote thegelation of the viscose. Although I prefer nickel equipment, I canconveniently use equipment made of materials such as glass, rubber,alkaliresisting molded compositions orthe commercial alloys known as"Iilium", either alone or in combination. The preferred viscose, whichis delivered to the extrusion devices without change in quality, enablesme to spin in a more orderly manner and at higher tensions which aresubstantially constant at all times. Furthermore, due to the fact that Iapply substantially imiform tension, I am able to spin high qualitythread at very h gh speeds, namely, 3000 or more inches per minute.

Any suitable viscose solution may be used in the present process.Satisfactory results are secured with viscoses prepared from aged alkalicellulose and xanthated with to 60 or more parts by weight based on thecellulose. The preferred viscose of this type contains 7% cellulose, 6%alkali and has a salt index of 8. Satisfactory results are also obtainedby utilizing viscose solutions prepared from cellulose xanthated withnot more than 25 parts by weight based on the cellulose, such as setforth in my copending applimtion Serial No. 501,478.

'Ihe spinning bath contemplated by the instart invention contains a.concentration of sulphuric acid which will exert a plasticizing effecton the freshly produced thread. In general, a spinning bath containingat least of acid will produce satisfactory results, although bathscontaining up to 85%, or indeed more, may also be used.

The total bath travel of the thread in the acid .bath will vary withinwide limits, depending partly on the sine of the thread being produced.For example, in making a 100 denier-40 filament thread, a bath travel offrom 10 to 40 inches has given satisfactory results. In methods orprocesses producing threads of larger denier and larger filaments, thebath travel thrmightheacidbathwiilbeasmuchasm inches or indeed more. Onthe other hand, with thread of fine denier and fine filaments, such as100 denier-100 filaments, the bath travel should, not exceed 15 to 20inches and may even beas small as 5 inches.

The travel of the thread in the water bath is of such distance as may benecessary to check the action of the acid.

The total tension which may be developed in the thread may vary from 0.1to 0.6 gram per denier or higher. In the preferred embodiment, the totaltension in the thread is developed progressively and in stages. It is tobe noted that by "total tension" I mean the tension on the threadbetween the last tension-applying device in the bath and the traverseguide (in the case of bobbin spinning) or .(in the case of bucketspinning) the feed wheel.

The instant invention contemplates spinning a thread at a high speed,such as not less than 3,000 inches per minute and indeed 3,600 inchesPer minute or higher.

The following examples are given to'further illustrate my invention,although I do not intend to be limited thereby:

Example 1.-100 parts of a high grade wood pulp, such as is commonly usedin the prepara tion of viscose, and containing 9% to 10%moisture, aresteeped in caustic soda of 17% to 20% strength at about 18 C. for 1 to 3hours. The excess caustic liquor is removed by pressing until the pressweight of the wet alkali cellulose is about 250 to 300 parts.\ Thealkali cellulose is then shredded for 2 to 3 hours and then aged at 20C. for to hours. The aged alkali cellulose is then xanthated, accordingto any well-known means. at 25' C. for 2 to 3 hours, using 33 parts ofcarbon bisulphide. 'ihe viscose solution is made by dissolving thecellulose xanthate in caustic soda solution at 18' C.'to produce asolution containing 7% cellulose and 6% alkali. This viscose is ripenedat 18 C. to a salt index of 8.0 (see Reinthaler and Rowe, "ArtificialSilk", 1928, page 68), at which index it is spun.

The viscose solution is conducted to the spinning room through nickelpipe lines, care being taken to prevent contamination in any form, andis spun into a bath containing about sulphuric acid which is maintainedat a temperature of 10' C. A small bobbin-type spinning machine is used,such as is manufactured by the Oscar Kohorn Co.

In the operation of the present process, and as diagrammaticallyillustrated in Figure 1, the spinning trough is divided into twocompartments I and I by a partition I running lengthwise on the machine.The front compartment I is filled with the acid-coagulating bath. Therear compartment 2 is filled with water maintained at a suitabletemperature for immediately quenching the strong acids.

A thread 4 is conducted a distance of 20 inches from a nozzle 5 to afloating roller 8 of the type described in Patent 1,878,455, and is ledaround this roller, and then returned about 5 inches to another floatingroller 1 which serves to apply more tension and also to change thedirection of travel of the thread. From the roller 1 the thread is ledto a rubber-covered rod I, up and across the partition I, separating theacid from the water bath. The thread travel in the water bath totalsabout 11 inches with the water flow preferably countercurrent to thedirection of the travel of the thread. Further tension is applied to thethread during its travel through the water bath by the use of two ormore floating roller guides 9 and II, as referred to above. Afterleaving the roller ill, the thread I passes under a rubber-covered hook:guide ll, thence over a traversing guide and onto a bobbin (not shown).

The thread is wound on a bobbin at a speed of 3,000 inches per minuteand under a final tension of about 0.4 gram per denier. The thread spunin this example is 100 denier-40 filament. so that the total tensionapplied is about 40 grams. Following the spinning operation, the threadis washed free from all traces of acid and dried in the customarymanner. If desired the thread may be desulphured and bleached priorEmple 2.--Vi'scose, as is prepared in Example 1, is spun at a salt indexof 8, using the bucket-type spinning machine instead ofthe bobbin-type,and spun into a spinning bath containing 64% to72%-aeid.

Figure 2, is led from a spinning nozzle a distance of about 20 inches,to a rotating guide ll of the type described in British Patent No. 318,-

-258. The thread passes around the rotor guide thread as it passes fromthe roller guides to the feed wheel is 0.14 to 0.25 gram per denier or,in the case of 100 denier-40 filament thread, 15 grams to 25 grams.

Example li -The mode of operation in this case is the same as in Example1, except that 15 parts .of carbon bisulphide per 100 parts of celluloseare used in preparing the viscose. Further, the viscose is not ripenedto a salt index of 8, but is spun immediately after mixing, or within ato 12 hour period of ripening at 18 C. following the mixing operation.The bath, in this case, contains 47% instead of 65% sulphuric acid.Other conditions are the same as in Ex' ample 1.

By the process which I have described, it is not-difiicult to produceartificial threads of uniform and good quality having a dry tenacity ofmore than 2 grams per denier, or even more than 3 or 4 grams per denier,and more than 2 grams per denier in the wet state.

The threads so produced are not only substantially free from brokenfilaments and fluff, but are much more uniform in tenacity, elongationand dyeing characteristics than high tenacity threads producedheretofore in plasticizing baths.

Although the viscose which I have specified in my examples is preparedfrom wood pulp, it may, of course, be made from cotton, cotton linters,hull fiber, or any other suitable cellulosie material. Further, it neednot be handled with the .care and equipment set forth in my copendingapplication Serial No. 676,463, v but may, of course, be handled in thecustomary manner although the results will be somewhat poorer.

It is obvious that the process may be conducted in ways other thanmentioned above, since the variables involved are interdependents andseveral of these variables may be concurrently varied without affectingthe nature of the product. For instance, viscose containing largeramounts of caustic may be spun in baths of higher acid concentration.Unaged or only slightly aged In this case, the thread It, asdiagrammatically illustrated in alkali cellulose yields 'viscoses whichrequire stronger acid for their plasticization. strength of the acid isalso dependent'upon the amount of cellulose in the viscose and upon thesalt index to which the viscose is ripened. Such factors as bath travel,tension applied to the thread at different stages in its travel, methodof washing, or the agent used for quenching may be changed withoutdeparting from the spirit of my invention.

Though the invention has been particularly described in connection withthe manufacture of artificial thread, it is not restricted thereto. Itis equally applicable to the manufacture of ribbons, films, straw,horsehair, etc.

I claim l. A method of producing artificial filaments. threads, straw,horsehair, ribbons, films, etc., which comprises extruding a viscosesolution into a bath containing at least 45% sulphuric acid, imposing asubstantially uniform and constant tension of at least 0.1 gram perdenier andwithout any undue sliding friction on the structureintermediate the extruding device and draw-oil device, checking theaction of the acid on the structure prior to the production of anydeleterious results, and winding the structure in an operation combinedwith the production of the same at a speed not less than 3,000 inchesper minute. a

2. A method of producing artificial filaments, threads, straw,horsehair, ribbons, films, etc., which comprises preparing a viscosesolution free from deleterious contaminations, delivering said viscosesolution without changing the quality thereof to the extruding device,extruding the viscose solution into a bath containing at least 45%sulphuric acid, imposing a substantially uniform and constant tension ofat least 0.1 gram per denier and without anyundue sliding friction onthe structure intermediate the extruding device and drawoft device,checking the action of the acid on the structure prior to the productionof any deleterious results, and winding the structure in an operationcombined with the production of the same at a speed not less than 3.000inches per minute.

3. A method of producing artificial filaments, threads, straw,horsehair, ribbons,films, etc.,which comprises preparing a viscosesolution free from deleterious contaminations, delivering said viscosesolution through equipment which is not corroded by said viscose anddoes not contaminate said viscose to the extruding device, extruding theviscose solution into a bath containing at least 45% sulphuric acid,imposing a substantially uniform and constant tension of at least 0.1gram per denier without any undue slid- I ing friction on the structureintermediate the extruding device and draw-off device, checking theaction of the acid on the structure prior to the production of anydeleterious results, and

winding the structure in an operation combined with the production ofthe same at a speed not less than 3,000 inches per minute.

4. A process of preparing artificial filaments. threads, straw,horsehair, ribbons, films, etc., which comprises preparing a viscosesolution having the desired salt index, delivering said viscose solutionwithout changing the quality thereof to the extruding device, extrudingthe viscose solution into a bath containing at least 45% sulphuric acid,imposing a substantially uniform and constant tension of at least 0.1gram per denier and without any undue sliding friction on the The'anoperationcombinedwiththeproductionotthesameataspeednotleasthanSMOinches perminute.

$.Amethodotpreparhigarflflcislillaments,

threads. straw, horsehair, ribbons, films, etc..

which comprises preparin: a viscon solution of the desired salt index,deliveringsaidviscose solutionthmmheq llvmentwhichisnotcorroded by saidviscose and does not contaminate said mumstureinanoperatimcombrlnedi'iththeproductimoithesamataspeednotlessthanSMinchesperminuta mnom may r m

